JUBA  - US President Barack Obama has warned that South Sudan stands at the “precipice” of civil war amid spiralling violence, with the UN launching a rescue mission after three Indian peacekeepers were killed.

The United Nations Security Council readied emergency consultations on the crisis in the world’s youngest nation, amid fears that fighting between rival army factions could escalate into full-scale civil war.

The UN said incidents of fighting or civil unrest, which began a week ago in the capital Juba, had now spread to 14 separate sites - including in the powder-keg eastern state of Jonglei - and that 34,000 terrified civilians were seeking protection in or around UN bases.

Neighbouring Uganda deployed troops Friday at the invitation of Juba to help secure the troubled capital and protect Ugandan citizens, Uganda’s government-owned New Vision newspaper reported.

Obama, who announced Thursday he had deployed 45 troops to the violence-wracked country, called for an immediate end to the unrest which has so far left close to 500 dead, most of them civilians.

“Recent fighting threatens to plunge South Sudan back into the dark days of its past,” he said. “South Sudan stands at the precipice.” Recalling the promise and hopes that accompanied South Sudan’s independence in July 2011, Obama warned “that future is at risk.”

Over two million people died in the brutal 1983-2005 civil war, which ended in a peace deal that paved the way for the oil-rich but impoverished South’s independence two years ago.

India’s UN envoy Asoke Mukerji said three Indian peacekeepers were “targeted and killed” during Thursday’s attack by ethnic Nuer youths on a base at Akobo in Jonglei state, an area awash with guns and home to several large rebel armies.

Other casualties are feared as the fate of more than 30 ethnic Dinka civilians sheltering at the base is not known, said UN deputy spokesman Farhan Haq.

The UN mission in South Sudan (UNMISS) said Friday it had sent four helicopters to pull out some 40 UN peacekeepers out of Akobo, saying it has “received assurances from forces in charge” of the remote town they would not be attacked.

The attack on the UN base came after troops loyal to fugitive former vice president Riek Machar seized the town of Bor late Wednesday, as heavy fighting continued in several sites across the vast swamplands and remote bush of Jonglei state.

President Salva Kiir has blamed the bloodshed on a coup bid by his perennial rival Machar, who was sacked as vice president in July.

Machar has denied mounting a coup, and has accused the president of trying to cover up a vicious purge. He is now calling for Kiir’s ouster, and the conflict has been taking on an ethnic dimension - with Kiir coming from the majority Dinka people and Machar from the Nuer.

UN human rights chief Navi Pillay has also expressed deep concern over reports of “numerous extrajudicial killings” and “civilians killed in Juba based on their ethnicity,” while UN chief Ban Ki-moon said the crisis “urgently needs to be dealt with through political dialogue”.

Human Rights Watch said witnesses had reported horrific cases of both soldiers and rebels executing people based on their tribe.

The UN peacekeeping mission said it was sheltering civilians in six state capitals, including Juba and Bor, as well as in Bentiu, the main town of the crucial petroleum-producing state of Unity.

At least five oil workers were killed in Unity when attackers broke into their compound late on Wednesday, a company official said. Oil production accounts for more than 95 percent of South Sudan’s fledgling economy.

Foreigners were being evacuated from the troubled country, with the United States and Britain sending in flights for their citizens, and others fleeing overland south to Uganda.

Long lines of aid workers and expatriates crowded Juba’s airport waiting to board the first flight they could out of the country.

Foreign ministers from five regional countries flew in Thursday to try to launch peace efforts, with Ethiopian Foreign Minister Tedros Adhanom leading the team from Djibouti, Kenya, Sudan and Uganda.

All are members of a regional body, the Inter-Governmental Authority on Development, whose members played key roles in pushing forward the 2005 deal that ended Sudan’s two-decade long civil war with the south.

The team, who are expected to meet with Kiir as well as several former powerful ministers arrested in connection with the violence, aims to “set up a ‘national dialogue platform’” to bring leaders together, Ugandan Foreign Minister Okello Oryem said Friday, according to a Ugandan government statement.